JP7037494B2 - Spherical boron nitride fine powder, its production method and a heat conductive resin composition using it - Google Patents

Description

The present invention relates to a spherical boron nitride fine powder, a method for producing the same, and a heat conductive resin composition using the same.

In recent years, electronic members are required to be miniaturized, and members such as heat radiating sheets used for the electronic members are also required to be thinned.

The heat dissipation filler used in electronic parts is often a combination of a coarse powder of several μm to several tens of μm and a fine powder of submicron to several μm, but the role of the fine powder is important for reducing the interfacial thermal resistance. Is.

For heat-dissipating fillers, especially fine powders, spherical particles are desirable, but what has been originally applied is mainly spherical alumina fine powders, and examples of applying spherical boron nitride fine powders as heat-dissipating fillers are examples. do not have.

Boron nitride is generally obtained by reacting a boron source (boric acid, borax, etc.) with a nitrogen source (urea, melamine, ammonia, etc.) at a high temperature, and scaly primary particles are formed from boric acid and melamine. Aggregated "pine-shaped" boron nitride (Patent Document 1), spherical boron nitride produced by a spray-drying method (Patent Document 2), and the like are known.
On the other hand, in the gas phase synthesis method, a method of obtaining spherical boron nitride fine powder has been reported (Patent Document 3, Patent Document 4 and Patent Document 5).
For scaly boron nitride, Patent Document 6 is known for improving the filling property by surface treatment, and Patent Document 6 describes a step of mechanically chemical treating scaly boron nitride in the presence of water or an organic solvent. A method for producing modified boron nitride, which is characterized by having the same, is described.

Japanese Unexamined Patent Publication No. 09-202663 Japanese Unexamined Patent Publication No. 2014-40341 Japanese Unexamined Patent Publication No. 2000-237312 Japanese Unexamined Patent Publication No. 2004-182572 International Publication 2015/12239 Japanese Unexamined Patent Publication No. 2015-36361

Since the aggregated particle size of boron nitride produced by the methods as in Patent Document 1 and Patent Document 2 is several tens of μm or more and is large particles, an extremely small and spherical boron nitride fine powder as in the present invention can be obtained. It was difficult to make.
There is no example in which the spherical boron nitride fine powder described in Patent Documents 3 to 5 is applied to a thermally conductive filler. This is because boron nitride produced by the conventional vapor phase synthesis method has a smaller number of functional groups on the surface than the oxide filler and has poor filling property as compared with the oxide filler.
In the modified boron nitride fine powder described in Patent Document 6, the effect of improving the filling property by the surface treatment of the scaly boron nitride is small, and the improvement of the filling property into the heat conductive resin composition is not recognized.
Therefore, it is a main object of the present invention to provide a spherical boron nitride fine powder having excellent filling property, a method for producing the same, and a heat conductive resin composition using the same.

As described above, since the surface in the thickness direction, which is said to have many functional groups in ordinary scaly boron nitride, is absent or extremely few on the surface, the filling property is poor even if the conventional surface treatment method is used, and the effect is sufficient. Could not be expressed. Further, since the spherical boron nitride fine powder generally has few surface functional groups, it has been said that the effect of the coupling treatment is not recognized.

Therefore, the present inventors have diligently studied for the purpose of improving the filling property with respect to the spherical boron nitride fine powder.
As a result, the present inventors apply a special surface modification treatment to the particle surface of the spherical boron nitride fine powder having a specific average particle size and shape before reacting with the metal coupling agent to obtain the spherical particles. It has been found that a spherical fine powder having an organic functional group on the surface can be obtained. It has been found that the spherical boron nitride fine powder in which this organic functional group is present has much better filling property than the conventional product.
Further, in the present invention, it has been found that the effect of the coupling treatment can be exhibited by subjecting the particle surface of the spherical boron nitride fine powder to a special modification treatment.
In this way, the present inventor has completed the present invention. That is, the present invention can provide the following [1] to [7].

The present invention can provide a spherical boron nitride fine powder characterized by having [1] or less (A) to (C).
(A) One or two of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga and V having a composition of 0.1 atm% or more and 3.0 atm% or less on the surface of spherical boron nitride fine particles at 10 nm. The above exists;
(B) The average particle size of the spherical boron nitride fine powder is 0.05 μm or more and 1 μm or less;
(C) The average circularity of the spherical boron nitride fine powder is 0.8 or more.
[2] The spherical boron nitride fine powder of the present invention can further have an organic functional group present on the surface of (D) spherical boron nitride fine particles.
[3] In the spherical boron nitride fine powder of the present invention, the organic functional group existing on the surface of the spherical boron nitride fine particles is an epoxy group which may have a substituent, a styryl group which may have a substituent, and the like. It has an alkyl group which may have a substituent, a vinyl group which may have a substituent, an acetylacetate group which may have a substituent, an acyl group which may have a substituent, and a substituent. It can be one or more selected from an isocyanate group which may have a substituent, a cyclohexyl group which may have a substituent, and a tetraoctylbis group which may have a substituent.
[4] The spherical boron nitride fine powder of the present invention is a raw material, a spherical boron nitride fine powder having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more, and wet pulverized by adding an oxidizing agent. Alternatively, it can be obtained by subjecting the surface of the particles to a surface modification treatment by wet crushing and further reacting with a metal coupling agent.
[5] In the spherical boron nitride fine powder of the present invention, an oxidizing agent and a water-soluble solvent can be added at the time of the surface modification treatment.
[6] In the spherical boron nitride fine powder of the present invention, the metal coupling agent is one selected from a metal alkoxide having an organic functional group, a metal chelate having an organic functional group, and a metal halogen compound having an organic functional group. It can be more than one kind.
[7] The present invention can provide a heat conductive resin composition containing the spherical boron nitride fine powder according to any one of [1] to [6] above.

According to the present invention, it is possible to provide a spherical boron nitride fine powder having excellent filling property. The effects described here are not necessarily limited, and may be any of the effects described in the present specification.

Hereinafter, suitable embodiments for carrying out the present invention will be described. It should be noted that the embodiments described below show an example of a typical embodiment of the present invention, and the scope of the present invention is not narrowly interpreted by this.

<1. Spherical boron nitride fine powder of the present invention>
The present invention is a spherical boron nitride fine powder having the following (A) to (C). Further, in the present invention, it is desirable that an organic functional group is present on the surface of the (D) spherical boron nitride fine particles.
(A) One or two of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga and V having a composition of 0.1 atm% or more and 3.0 atm% or less on the surface of spherical boron nitride fine particles at 10 nm. The above exists;
(B) The average particle size of the spherical boron nitride fine powder is 0.05 μm or more and 1 μm or less;
(C) The average circularity of the spherical boron nitride fine powder is 0.8 or more.

Regarding the "spherical boron nitride fine powder" of the present invention, Si, Ti of 0.1 atm% or more and 3.0 atm% or less in the composition in the surface of the spherical boron nitride fine particles after surface treatment at 10 nm by X-ray photoelectron spectroscopy. , Zr, Ce, Al, Mg, Ge, Ga and V, it is desirable that one or more of the metal elements are present.
Of these, one or more selected from Si, Ti, Zr and Al are preferable in terms of easy availability of the metal coupling agent.
If the amount of metal element is less than 0.1 atm% in the surface of spherical boron nitride fine particles after surface treatment of 10 nm, the effect of improving the filling property is not sufficient, and if it exceeds 3.0 atm%, the thermal conductivity decreases when used as a filler. It may happen.

Regarding the "spherical boron nitride fine powder" of the present invention, the average particle size of the spherical boron nitride fine powder after surface treatment is preferably 0.05 to 1.0 μm, and further 0.1 to 1.0 μm. Is preferable.
If the average particle size of the fine powder is less than 0.05 μm, the increase in viscosity when mixed with the resin may increase even if surface treatment is applied, while if it exceeds 1.0 μm, during gas phase synthesis. It is not preferable because the yield is significantly reduced.

Regarding the "spherical boron nitride fine powder" of the present invention, the average circularity of the spherical boron nitride fine powder after surface treatment is 0.8 or more because it improves the filling property and reduces the influence of orientation. It is preferably 0.9 or more, and more preferably 0.9 or more.

Regarding the "spherical boron nitride fine powder" of the present invention, it is desirable that an organic functional group is present on the surface of the fine particles of spherical boron nitride after the surface treatment. The organic functional group is not particularly limited. For example, the metal element and the organic functional group of the commercially available metal coupling agent can be appropriately present on the surface of the fine particles by the surface treatment method of the present invention. Further, as the organic functional group, an organic functional group having compatibility with the resin of the heat conductive resin composition to be filled may be appropriately selected.

The organic functional group existing on the surface of the "spherical boron nitride fine particles" may have, for example, an epoxy group which may have a substituent, a styryl group which may have a substituent, and a substituent. An alkyl group, a vinyl group which may have a substituent, an acetylacetate group which may have a substituent, an acyl group which may have a substituent, an isocyanate group which may have a substituent, and a substituent. Examples thereof include a cyclohexyl group which may have a substituent, a tetraoctylbis group which may have a substituent, and the like. These may be organic functional groups with or without substituents. One or two or more can be selected from these.

Examples of the epoxy group which may have the substituent include an epoxy group and the like.
Examples of the aryl group which may have the substituent include a styryl group and the like.
As the alkyl group which may have a substituent, for example, a propyl group which may have a substituent (for example, a methacryloxypropyl group, an acryloxypropyl group, an aminoethylaminopropyl group, a glycidoxypropyl group, etc. Examples thereof include a phenylaminopropyl group) and an alkyl group having 5 or more linear carbon atoms (preferably 5 to 25 linear carbon atoms).
Examples of the vinyl group which may have the substituent include a vinyl group, a styryl group, an acetylacetonate group, a methacryloyl group and the like.
Examples of the acetylacetonate group which may have the substituent include an acetylacetonate group and the like.
Examples of the acyl group which may have the substituent include an acetylacetonate group, an isopropyltriisostearoyl group, a methacrylic group, a methacryloyl group and the like.
Examples of the isocyanate group include an isocyanate group.
Examples of the cyclohexyl group which may have a substituent include a cyclohexyl group and the like.
Examples of the tetraoctylbis (ditridecylphosphite) group which may have a substituent include a tetraoctylbis (ditridecylphosphite) group.
One or two or more can be selected from these.

Examples of the organic functional group present on the surface of the "spherical boron nitride fine particles" include an epoxy group, a styryl group, a methacryloxypropyl group, an acryloxypropyl group, an aminoethylaminopropyl group, a glycidoxypropyl group and a phenylamino. Alkyl with 5 or more propyl group, acetylacetonate group, vinyl group, methacryl group, methacryloyl group, isopropyltriisostearoyl group, tetraoctylbis (ditridecylphosphite) group, cyclohexyl group, isocyanate group and linear carbon number of 5 or more. The group etc. can be mentioned. One or two or more can be selected from these.
Of these, an epoxy group, a styryl group, a glycidoxypropyl group, an acetylacetonate group, a vinyl group, an isopropyltriisostearoyl group, a tetraoctylbis (ditridecylphosphite) group, a cyclohexyl group and an isocyanate group are more preferable. be.
One or two or more can be selected from these.

<2. Method for producing surface-treated spherical boron nitride fine powder of the present invention>
In the production method of the present invention, an oxidizing agent is added to a raw material, spherical boron nitride fine powder (first spherical boron nitride fine powder) having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more. In addition, it is a method of obtaining a surface-treated spherical boron nitride fine powder by subjecting the particles to surface modification treatment by wet pulverization or wet pulverization and further reacting with a metal coupling agent.

<Manufacturing method of spherical boron nitride fine powder before surface treatment in the manufacturing method of the present invention>
The spherical boron nitride fine powder before surface treatment, which is used as a raw material for the production method of the present invention, is not a solid phase method, which is a conventional method for producing hexagonal boron nitride, but a tubular furnace in an inert gas stream. After performing so-called gas phase synthesis using volatile boron nitride and ammonia as raw materials (first firing condition), then firing in a resistance heating furnace (second firing condition), and finally. In addition, this calcined product can be synthesized by putting it in a boron nitride-made rutsubo and calcining it in an induction heating furnace to produce boron nitride fine powder (third calcining condition).
As a result, a spherical boron nitride fine powder (first spherical boron nitride fine powder) having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more can be obtained.
The spherical boron nitride fine powder used as a raw material can be produced with reference to Patent Document 5 (International Publication No. 2015/12237).
Further, since it is desirable to have high purity and high crystals for use for this purpose, it is preferable to calcin at 1,800 to 2,200 ° C. under a nitrogen atmosphere under the third calcination condition.

Under the first firing conditions, a tubular furnace (furnace temperature 750 to 1,100 ° C.) is used to perform so-called gas phase synthesis using boron alkoxide volatilized in an inert gas stream and ammonia gas as raw materials. , The first calcined powder (boron nitride white powder) can be obtained. This makes it possible to keep the average particle size of the boron nitride particles in a predetermined range.
Examples of the type of the inert gas stream include nitrogen gas, noble gas (neon, argon, etc.) and the like.
The first firing condition is preferably 750 to 1,100 ° C.
The reaction time between the boric acid alkoxide and ammonia is preferably 30 seconds or less in order to keep the average particle size of the boron nitride powder as a raw material within a predetermined range.
The boric acid alkoxide is not particularly limited, but the "alkyl group (R)" of the "alkoxide (RO-)" may be the same or different, but a linear or branched chain having 1 to 5 carbon atoms is preferable. .. Examples of the borate alkoxide include trimethyl borate, triethyl borate, and triisopropyl borate. Of these, trimethyl borate is preferable because of its reactivity with ammonia and availability.
The molar ratio of boric acid alkoxide: ammonia is preferably 1: 1 to 10, and more preferably 1: 1 to 2 in order to keep the average particle size of the raw material boron nitride powder within a predetermined range.

Under the second firing conditions, the first firing powder can be fired in an atmosphere in a resistance heating furnace, cooled, and then a second fired product can be obtained. This makes it possible to keep the average circularity of the boron nitride powder as a raw material within a predetermined range.
The temperature of the second firing condition is preferably 1,000 to 1,600 ° C, more preferably 1,200 to 1,500 ° C.
The reaction time under the second firing condition is preferably 1 hour or longer, more preferably 1 to 20 hours, and even more preferably 1 to 10 hours.
Examples of the atmosphere of the second firing condition include ammonia gas, a mixture of ammonia gas and an inert gas, and the like. Further, a mixed atmosphere of ammonia gas and nitrogen gas (preferably 50 to 90 vol% of ammonia: 10 to 50 vol% of nitrogen) is preferable.

Under the firing condition 3, the second fired product is fired in an induction heating furnace in a nitrogen atmosphere to produce boron nitride fine powder used as the raw material of the present invention.
The temperature of the third firing condition is preferably 1,000 to 3,000 ° C, more preferably 1,500 to 2,500 ° C, and even more preferably 1,800 to 2,200 ° C.
The time of the third firing condition is preferably 0.5 hours or more, more preferably 0.5 to 20 hours, and more preferably 1 to 10 hours.

<Method for surface treatment of raw material fine particles in the production method of the present invention>
Regarding the "surface modification treatment of particles" in the production method of the present invention, an oxidizing agent is added to a spherical boron nitride fine powder (first spherical boron nitride fine powder) having a specific average particle size and shape as a raw material and wet. It is desirable to perform surface modification treatment of the particles by crushing or wet crushing.
As a result, a surface-modified spherical boron nitride fine powder (second spherical boron nitride fine powder: also referred to as "surface-modified spherical boron nitride fine powder") that can be reacted with a metal coupling agent is obtained. Can be done.

The spherical boron nitride fine powder (first spherical boron nitride fine powder) obtained under the first firing conditions to the third firing conditions is used as a raw material for the production method of the present invention, and the following surface treatment method is performed. Can be done.
The spherical boron nitride fine powder as a raw material preferably has an average particle size of 0.05 μm or more and 1 μm or less, and an average circularity of 0.8 or more. The upper limit of the average circularity is 1.0.

The spherical boron nitride produced by gas phase synthesis is a fine powder of 1.0 μm or less, and its structure is an onion-like structure as if it is covered with the 002 surface of boron nitride, and is substantially spherical.
Therefore, in the spherical boron nitride fine powder, the surface in the thickness direction, which is considered to have many functional groups in ordinary scaly boron nitride, does not exist or is extremely small on the surface. It was so bad that the effect could not be fully expressed.
However, as a result of diligent studies, the present inventors generally add an oxidizing agent using a crusher or a crusher and perform a wet surface modification treatment of the particles before the coupling treatment. It was found that even a spherical boron nitride fine powder having few groups and no effect of the coupling treatment can exert the effect of the coupling treatment.

For the wet crushing and wet crushing used in the present invention, a known wettable crusher or crusher can be used.
The crusher or crusher is not particularly limited as long as it can perform wet surface modification such as a bees mill, a ball mill, a Henschel mixer, a jet mill, a starburst, and a paint conditioner, in addition to the locking mill used in the present invention. ..
Examples of the medium include zirconia balls and silicon nitride, and it is desirable to use them as appropriate.

The crushing or crushing treatment time is preferably 10 minutes or more and 5 hours or less, and more preferably 20 minutes or more and 2 hours or less. If the treatment time is less than 10 minutes, the effect of surface modification by crushing or crushing is not sufficiently obtained, and if the treatment is performed for more than 5 hours, the productivity is lowered, which is not preferable.
The frequency at the time of crushing or crushing is preferably 200 to 2000 rpm, more preferably 500 to 1500 rpm.

The oxidizing agent to be used is not particularly limited, and examples thereof include hydrogen peroxide, nitric acid, and permanganate. Of these, an oxidizing agent that is soluble in a solvent and easily removed after treatment is desirable. Further, hydrogen peroxide and a compound having an oxidizing power equal to or higher than that of hydrogen peroxide, which is soluble in a solvent and easily removed after treatment (for example, nitric acid) are desirable. From these, one kind or a combination of two or more kinds may be used. It is desirable to use only water as the solvent depending on the oxidizing agent selected.
By using an oxidizing agent in combination with the crushing / crushing treatment, the surface is modified more efficiently, the dispersibility is improved, the surface functional groups are increased, and the coupling reaction proceeds efficiently.

The amount of the oxidizing agent used is preferably 30 to 200 parts, more preferably 50 to 150 parts with respect to 100 parts of boron nitride.
A water-soluble solvent is preferable as the solvent to be mixed with the oxidizing agent. Examples of the water-soluble solvent include one or more selected from water, alcohol, dioxane and the like. Elemental water and / or alcohol are preferred. The alcohol preferably has a linear or branched alkyl group, and the alkyl group preferably has 1 to 3 carbon atoms (for example, methanol, ethanol, propyl alcohol, isopropyl alcohol, etc.). More preferably, it is water, an alcohol having 1 to 3 carbon atoms, and a mixed solution thereof.
The mixing ratio of the oxidizing agent and the solvent is preferably 1 to 10 parts, more preferably 2 to 7 parts with respect to 100 parts of the solvent.

<Surface treatment method for adding an organic functional group in the production method of the present invention>
Regarding the "organic functional group surface treatment method" in the production method of the present invention, the spherical boron nitride fine powder (surface-modified spherical boron nitride fine powder) subjected to the special surface modification treatment further has an organic functional group. React with a metal coupling agent.
As a result, a spherical boron nitride fine powder (third spherical boron nitride fine powder: hereinafter also referred to as “surface-treated spherical boron nitride fine powder”) in which a metal element and an organic functional group are present on the surface of the spherical boron nitride fine particles can be obtained. Can be done.

The surface treatment method for metal elements and organic functional groups for surface-modified spherical boron nitride fine particles in the present invention is a spherical boron nitride fine particles having an average particle size of 0.05 μm or more and 1.0 μm or less and an average circularity of 0.8 or more. It is preferable to use the powder as a raw material and perform a surface modification treatment of the powder by adding an oxidizing agent by wet pulverization or wet crushing, and then reacting with a metal coupling agent.

It is desirable to filter and wash the sieved slurry of the boron nitride fine powder after the modification treatment of the powder surface. The cleaning liquid is not particularly limited, and for example, a solvent to be mixed with the oxidizing agent may be used.
The temperature of the coupling reaction condition is preferably 10 to 70 ° C, more preferably 20 to 70 ° C.
The time of the coupling reaction condition is preferably 0.2 to 5 hours, more preferably 0.5 to 3 hours.
The solvent for the metal coupling reaction is not particularly limited, and examples thereof include alcohol (preferably a linear or branched chain having 1 to 5 carbon atoms), acetone, furan and the like. Of these, methanol, ethanol, propyl alcohol, isopropyl alcohol and acetone are preferable. These may be used alone or in combination of two or more.
The amount of the solvent used in the metal coupling reaction is preferably 100 to 2000 parts, more preferably 600 to 1200 parts with respect to 100 parts of boron nitride.
The amount of the metal coupling agent used is not particularly limited, but is preferably 0.5 to 10 parts, and more preferably 1 to 5 parts with respect to 100 parts of boron nitride.

In the present invention, the metal coupling agent is not particularly limited. As shown in [Example] below, even if various metal coupling agents were used, the metal element and the organic functional group could be present on the surface of the spherical boron nitride fine particles. Therefore, in the present invention, as appropriate. The desired metal coupling agent can be used.
Further, it is preferable to select a coupling agent according to the resin to be used. This makes it possible to obtain a boron nitride powder having good compatibility with the resin used in the heat conductive resin composition.
Examples of the metal coupling agent include metal alkoxides, metal chelates, metal halides and the like. These can be used alone or in combination of two or more.
The metal element of the metal coupling agent includes, for example, one or more selected from Si, Ti, Zr, Ce, Al, Mg, Ge, Ga and V, and is not particularly limited. ..

The amount of the metal coupling agent treated is a value obtained by X-ray photoelectron spectroscopy, and the composition in the surface of the spherical boron nitride fine particles of 10 nm is 0.1 atm% or more and 3.0 atm% or less of Si, Ti, Zr, Ce, Al. , Mg, Ge, Ga and V, it is desirable to add one or more metal elements so as to be present.
If the metal element is less than 0.1 atm%, the effect of improving the filling property is not sufficient, and if the metal element exceeds 3.0 atm%, the thermal conductivity may decrease when used as a filler.

Examples of the metal coupling agent include a titanium coupling agent, a silane coupling agent, a zirconium coupling agent, an aluminum coupling agent, and the like in terms of easy availability of the metal coupling agent. These can be used alone or in combination of two or more.

Examples of the titanium coupling agent include isopropyltriisostearoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, and tetraoctylbis (ditridecylphosphite). ) Titanium, Tetra (2,2-diallyloxymethyl) bis (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltrioctanoyl titanate, isopropyldimethacryliso Stearoyl titanate, isopropylisostearoyl dialicyl titanate, isopropyltri (dioctyl phosphate) titanate, isopropyltricylphenyl titanate, isopropyltri (N-aminoethyl / aminoethyl) titanate, dicumylphenyloxyacetate titanate, diisostearoyl ethylene titanate, etc. Can be mentioned.
Of these, isopropyltriisostearoyl titanate (metal alkoxide), tetraisopropylbis (dioctylphosphite) titanate (metal chelate), and tetraoctylbis (ditridecylphosphite) titanate (metal chelate) are preferable.

Examples of the silane coupling agent include vinylsilanes such as vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, and vinyltrimethoxysilane; γ-methacryloxypropyltrimethoxysilane; β- (3, 4-Epoxycyclohexyl) Epoxysilanes such as ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane; N-β- (aminoethyl) -γ-aminopropyltrimethoxy Aminosilanes such as silanes, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilanes, γ-aminopropyltrimethoxysilanes, N-phenyl-γ-aminopropyltrimethoxysilanes; and other silane coupling agents. Examples thereof include γ-mercaptopropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, and γ-chloropropylmethyldiethoxysilane.
Of these, preferably 3-glycidyloxypropyltrimethoxysilane, p-styryltrimethoxysilane (metal alkoxide), 3-isocyanatepropyltriethoxysilane (metal alkoxide), vinyltrimethoxysilane (metal alkoxide), cyclohexylmethyl Dimethoxysilane (metal alkoxide).

Examples of the zirconium coupling agent include tetra-n-propoxyzirconium, tetra-butoxyzirconium, zirconium tetraacetylacetonate, zirconium dibutoxybis (acetylacetonate), zirconium tributoxyethylacetate, and zirconium butoxyacetylacetonate. Examples thereof include bis (ethylacetate acetate) and tetrakis (2,4-pentandionate) zirconium.
Of these, tetrakis (2,4-pentanionate) zirconium (metal alkoxide) is preferable.

Examples of the aluminum coupling agent include aluminum isopropylate, monosec-butoxyaluminum diisopropyrate, aluminum sec-butyrate, aluminumetylate, ethylacetate acetylate aluminum diisopropyrate, aluminumtris (ethylacetoacetate), and alkyl. Examples thereof include acetoacetate aluminum diisopropyrate, aluminum monoacetylacetate bis (ethylacetate acetate), aluminum tris (acetylacetacetate), aluminum bisethylacetate acetate and monoacetylacetonate.
Of these, aluminum bisethylacetate acetate / monoacetylacetonate (metal chelate compound) is preferable.

The features of the spherical boron nitride fine powder (third spherical boron nitride fine powder) obtained by the method for producing the surface-treated spherical boron nitride fine powder of the present invention are described in <1. Spherical boron nitride fine powder of the present invention>.

<3. Thermal resin composition>
The heat conductive resin composition of the present invention can be obtained by containing the spherical boron nitride fine powder of the present invention or the spherical boron nitride fine powder obtained by the production method of the present invention. As a method for producing this heat conductive resin composition, a known production method can be used. The obtained heat conductive resin composition can be widely used for heat dissipation members and the like.
Further, it is preferable to use the spherical boron nitride fine powder of the present invention, which has high compatibility with the resin used as a raw material. Since the spherical boron nitride fine powder of the present invention has an organic functional group on the particle surface, a suitable spherical boron nitride fine powder is selected in consideration of the degree of compatibility between the organic functional group and the raw material resin. Or you can manufacture it.
Further, since the spherical boron nitride fine powder of the present invention can suppress the increase in viscosity when producing the heat conductive resin composition, it can also be applied to a high viscosity raw material resin. As described above, the spherical boron nitride fine powder of the present invention can be used for a wide range of raw material resins.

<Resin>
Examples of the resin used in the heat conductive resin composition containing the spherical boron nitride fine powder of the present invention include epoxy resin, silicone resin, silicone rubber, acrylic resin, phenol resin, melamine resin, urea resin, and unsaturated polyester. , Fluorine resin, polyamide (eg, polyimide, polyamideimide, polyetherimide, etc.), polyester (eg, polybutylene terephthalate, polyethylene terephthalate, etc.), polyphenylene ether, polyphenylene sulfide, total aromatic polyester, polysulfone, liquid crystal polymer, polyether. Asulfone, polycarbonate, maleimide-modified resin, ABS resin, AAS (acrylonitrile-acrylic rubber / styrene) resin, AES (acrylonitrile / ethylene / propylene / diene rubber-styrene) resin and the like can be used.
In particular, an epoxy resin (preferably a bisphenol A type epoxy resin, a naphthalene type epoxy resin, etc.) is suitable as an insulating layer for a printed wiring board because it has excellent heat resistance and adhesive strength to a copper foil circuit.
Further, the silicone resin is suitable as a thermal interface material because it has excellent heat resistance, flexibility, and adhesion to a heat sink or the like.

Specific examples of the epoxy resin curing agent include phenol novolac resin, acid anhydride resin, amino resin, and imidazoles. Of these, imidazoles are preferable.
The blending amount of the curing agent is preferably 0.5 parts by mass or more and 15 parts by mass or less, and more preferably 1.0 part by mass or more and 10 parts by mass or less.

The amount of the spherical boron nitride fine powder used in 100% by volume of the heat conductive resin composition is preferably 30% by volume or more and 85% by volume or less, and 40% by volume or more and 80% by volume with respect to the total amount of the epoxy resin and the curing agent. The following is more preferable.
When the amount of the spherical boron nitride fine powder used is 30% by volume or more, the thermal conductivity is improved and sufficient heat dissipation performance can be easily obtained. Further, when the content of the spherical boron nitride fine powder is 85% by volume or less, it is possible to reduce the tendency for voids to occur during molding, and it is possible to reduce the deterioration of the insulating property and the mechanical strength.

<Measurement method>
The spherical boron nitride powder used in the present invention was analyzed by the measurement method shown below. (1) Average particle size: A laser diffraction / scattering method particle size distribution measuring device manufactured by Beckman Coulter, (LS-13 320) was used to measure the average particle size. The obtained average particle size is the average particle size according to the volume statistics.
When the average particle size was less than 100 nm, a dynamic light scattering measuring device Zetasizer Nano ZS manufactured by MALVERN was used.

(2) Average circularity: After taking a particle image with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), the particles are subjected to image analysis (for example, manufactured by Mountech, trade name "MacView"). The projected area (S) and the peripheral length (L) were measured. The circularity was calculated by the following formula.
Average circularity: circularity = 4πS / L ²
The circularity was measured for 100 arbitrarily selected particles, and the average value thereof was taken as the average circularity of the sample. Microscopic photographs were analyzed at a magnification of 10,000 to 100,000, an image resolution of 1280 x 1024 pixels, and a manual recognition mode. The minimum particle size for measurement was 20 nm.

(3) Viscosity evaluation: As a method for preparing a sample for viscosity, a raw material resin "epoxy resin jER816A manufactured by Mitsubishi Chemical Corporation" was used, boron nitride powder was added, and the sample was passed through three rolls to prepare a sample for evaluation. When spherical boron nitride is used as a filler, a small amount is added in combination with a filler of coarse powder. Therefore, a resin having a low viscosity is used, and a sample is prepared with a filling amount of 5 vol% of boron nitride powder to create a low shear rate region. It can be evaluated by comparing.
The viscosity was evaluated using a rheometer with an MCR300 manufactured by Anton Pearl Co., Ltd., and the value of the viscosity at a shear rate of 0.01 1 / sec was used as the evaluation value. It can be judged that the lower the viscosity value, the higher the filling property, and a value of 20 Pa · sec or less was taken as a passing value.

(4) X-ray photoelectron spectroscopy analysis: For the analysis of the amount of metal on the surface of boron nitride, the treated powder is subjected to a K-Alpha type X-ray photoelectron spectroscopy device manufactured by Thermo Fisher. The measurement was performed at × 200 μm.
The semi-quantitative value of the detected metal element is estimated from the integrated value of the detected elements B, N, C, O and each metal, and this value is usually expressed by the atomic number ratio (atm%). The detection depth of the X-ray photoelectron spectroscope is 10 nm on the surface.

(5) Time-of-flight secondary ion mass spectrometry TOF-SIMS: Functional group analysis on the surface of boron nitride was performed by a time-of-flight secondary ion mass spectrometer PHI nanoTOF II manufactured by ULVAC FI Co., Ltd. From the results of mass spectrometry, when multiple fragment peaks derived from the coupling agent were detected, the detection item of the surface functional group was marked with ◯, and when not detected, it was marked with x.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[Example 1]
The surface-treated spherical boron nitride fine powder of Example 1 was synthesized by performing the first firing step to the third firing step and the surface treatment step in this order as shown below. Further, the obtained spherical boron nitride fine powder was filled in a resin to produce a heat conductive resin composition.

(Baking condition 1)
The core tube was installed in a resistance heating furnace and heated to a temperature of 1000 ° C. Trimethyl borate (“TMB-R” manufactured by Tama Chemical Co., Ltd.) is introduced into the core tube through the introduction tube by nitrogen bubbling, while ammonia gas (purity 99.9% or more) is also introduced into the core tube via the introduction tube. Introduced in. The introduced trimethyl borate and ammonia had a gas phase reaction in a furnace at a molar ratio of 1: 1.2, and were synthesized in a reaction time of 10 seconds to produce a white powder. The white powder produced was recovered.
(Baking condition 2)
The white powder recovered under the firing condition 1 is filled in a boron nitride rutsubo, set in a resistance heating furnace, and then heated at a temperature of 1350 ° C. for 5 hours in a nitrogen-ammonia mixed (1: 1) atmosphere. It was cooled and the fired product was collected.
(Baking condition 3)
The calcined product obtained under the calcining condition 2 was placed in a boron nitride rutsubo and fired in an induction heating furnace at 2000 ° C. for 4 hours to obtain a boron nitride fine powder.
The spherical boron nitride powder synthesized under the above firing conditions 1 to 3 had an average particle size of 0.05 μm or more and 1 μm or less, and an average circularity of 0.8 or more.

(Surface treatment conditions)
Synthesized spherical boron nitride powder was prepared using a locking mill manufactured by Seiwa Giken Co., Ltd. under the conditions of a frequency of 600 rpm and water: hydrogen peroxide = 1: 0.05 (wt% ratio) of 1400 parts per 100 parts of boron nitride. The treatment was carried out for 30 minutes, and the surface modification treatment was carried out.
A 0.3 mφ zirconia ball was used as the medium. Only the media of the treated slurry was separated with a 75 μm sieve, and the sieved slurry was filtered and washed.
After filtration, add 1000 parts of isopropyl alcohol to 100 parts of boron nitride and 4 parts of KR-TTS (isopropyltriisostearoyl titanate) manufactured by Ajinomoto Fine-Techno Co., Ltd. as a coupling agent, and treat at 70 ° C for 3 hours. And the coupling process was performed. The treated powder was filtered and washed, and then dried at 80 ° C. to obtain a surface-treated spherical boron nitride fine powder.

(Filling in resin)
50 parts by volume of the obtained surface-treated spherical boron nitride fine powder for 100 parts of naphthalene type epoxy resin (HP4032 manufactured by DIC) and 10 parts of imidazoles (2E4MZ-CN manufactured by Shikoku Chemicals Corporation) as a curing agent. After mixing to a thickness of 1.0 mm and applying the mixture on a PET sheet to a thickness of 1.0 mm, defoaming under reduced pressure of 500 Pa was performed for 10 minutes. Then, the sheet was pressed by pressing for 60 minutes under ^two conditions of a temperature of 150 ° C. and a pressure of 160 kg / cm to obtain a 0.5 mm sheet.

[Example 2]
In Example 2, a surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that the surface treatment condition was changed to “1 part of the amount of the coupling agent”.

[Example 3]
In Example 3, a surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that the surface treatment condition was changed to “30 parts of the amount of the coupling agent”.

[Example 4]
In Example 4, a surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that the firing condition 1 was “trimethyl borate and ammonia had a molar ratio of 1: 9”.

[Example 5]
In Example 5, a surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that the heating temperature of the firing condition 1 was set to 800 ° C.

[Example 6]
In Example 6, a surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that the temperature of the firing condition 2 was changed to 1500 ° C.

[Example 7]
Example 7 has the same conditions as Example 1 except that the coupling agent under the surface treatment conditions is changed to "KR-46B [Tetraoctyl-bis (ditridegylphosphite) titanate manufactured by Ajinomoto Fine-Techno Co., Ltd.]". A surface-treated spherical boron nitride fine powder was obtained.

[Example 8]
In Example 8, synthesis was carried out under the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions was changed to "Shinetsu Silicone X12-982S [polymer type epoxysilane type]", and the surface treatment was performed. Spherical boron nitride fine powder was obtained.

[Example 9]
In Example 9, the surface treatment was performed under the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions was changed to "manufactured by Tokyo Chemical Industry Co., Ltd. [3-glycidyloxypropyltrimethoxysilane]". Spherical boron nitride fine powder was obtained.

[Example 10]
In Example 10, the coupling agent under the surface treatment condition was changed to "Tetrakis (2,4-pentanionate) zirconium (IV (Japanese name: zirconium (IV) acetylacetonate)" manufactured by Tokyo Kasei Kogyo Co., Ltd.]. A surface-treated spherical boron nitride fine powder was produced under the same conditions as in Example 1 except for the modification.

[Example 11]
In Example 11, the coupling agent under the surface treatment condition was "Organix AL-3200 manufactured by Matsumoto Fine Chemical Co., Ltd. [Aluminum bisethylacetate acetate / monoacetylacetonate ((C ₅ H ₇ O ₂ ) (C ₆ H ₉ ). A surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except that it was changed to O ₃ ) ₂ )] ”.

[Example 12]
In Example 12, the surface-treated spherical nitride was subjected to the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions was changed to “KBM-140 [p-styryltrimethoxysilane] manufactured by Shinetsu Silicone”. Boron fine powder was obtained.

[Example 13]
Example 13 is a spherical surface-treated sphere under the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions is changed to "KBE-9007 [3-isocyanatepropyltriethoxysilane] manufactured by Shinetsu Silicone". Boron nitride fine powder was obtained.

[Example 14]
In Example 14, the spherical surface was treated under the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions was changed to "Z-6300 [vinyltrimethoxysilane] manufactured by Toray Dow Coating". Boron nitride fine powder was obtained.

[Example 15]
Example 15 is a spherical surface-treated sphere under the same conditions as in Example 1 except that the coupling agent under the surface treatment conditions is changed to "Z-6187 [cyclohexylmethyldimethoxysilane] manufactured by Toray Dow Coating". Boron nitride fine powder was obtained.

[Example 16]
In Example 16, except that "water: hydrogen peroxide = 1: 0.05 (wt% ratio) 1400 parts" was changed to "water: nitrite = 1: 0.05 (wt% ratio) 1400 parts". Under the same conditions as in Example 1, a surface-treated spherical boron nitride fine powder was obtained.

[Example 17]
In Example 17, "water: hydrogen peroxide = 1: 0.05 (wt% ratio) 1400 parts" was changed to "water: permanganate = 1: 0.03 (wt% ratio) 1400 parts". A surface-treated spherical boron nitride fine powder was obtained under the same conditions as in Example 1 except for the above.

[Comparative Example 1]
In Comparative Example 1, boron nitride fine powder was obtained under the same conditions as in Example 1 except that the “surface modification treatment and the coupling treatment” were not performed.

[Comparative Example 2]
In Comparative Example 2, boron nitride fine powder was obtained under the same conditions as in Example 1 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

[Comparative Example 3]
In Comparative Example 3, boron nitride fine powder was obtained under the same conditions as in Example 1 except that “hydrogen peroxide was not added during the surface modification treatment”.

[Comparative Example 4]
In Comparative Example 4, boron nitride fine powder was obtained under the same conditions as in Example 1 except that the molar ratio of trimethyl borate and ammonia was 1:12.

[Comparative Example 5]
In Comparative Example 5, boron nitride fine powder was obtained under the same conditions as in Example 1 except that the firing time of the firing condition 2 was set to 10 minutes.

[Comparative Example 6]
In Comparative Example 6, boron nitride fine powder was obtained under the same conditions as in Example 7 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

[Comparative Example 7]
In Comparative Example 7, boron nitride fine powder was obtained under the same conditions as in Example 8 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

[Comparative Example 8]
In Comparative Example 8, boron nitride fine powder was obtained under the same conditions as in Example 9 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

[Comparative Example 9]
In Comparative Example 9, boron nitride fine powder was obtained under the same conditions as in Example 10 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

[Comparative Example 10]
In Comparative Example 10, boron nitride fine powder was obtained under the same conditions as in Example 11 except that “rocking mill treatment as surface modification treatment during surface treatment” was not performed.

The measurement results of the spherical boron nitride fine powder of Examples 1 to 17 and the boron nitride fine powder of Comparative Examples 1 to 10 are shown in Tables 1 to 3.

The viscosities of the spherical BN fine powders of Examples 1 to 17 were approximately 10 Pa · S or less. Most of the BN fine powders of Comparative Examples 1 to 10 had a viscosity of around 190 Pa · s, and even the lowest BN fine powder of Comparative Example 3 was 50 Pa · s. The viscosities of the spherical BN fine powders of Examples 1 to 17 were at least 1/5 to 1/10 as compared with the viscosity of Comparative Example 3, which was the lowest among the comparative examples.
As described above, the spherical BN fine powder of the present invention is a novel powder having a very excellent filling property because the viscosity is remarkably lower than the conventional one. Further, even if various organic functional groups were present on the surface, the filling property into the resin was good. When an oxidizing agent of hydrogen peroxide, nitric acid, or permanganate was used in the surface treatment, the filling property into the resin was good. The spherical BN portion powder of the present invention having improved filling property can be obtained by subjecting the special surface treatment of the present invention. By using the spherical boron nitride fine powder of the present invention, an excellent heat conductive resin composition can be provided.

The surface-treated spherical boron nitride fine powder of the present invention can be widely used for heat-dissipating members and the like.

The present technology can also adopt the following [1] to [10].
[1] The surface of the particles is modified by wet pulverization or wet crushing by adding an oxidizing agent to the raw material, spherical boron nitride fine powder having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more. A method for producing a surface-treated spherical boron nitride fine powder, which comprises performing a quality treatment and further reacting with a metal coupling agent.
[2] The method for producing a surface-treated spherical boron nitride fine powder according to the above [1], wherein an oxidizing agent and a water-soluble solvent are added at the time of the surface modification treatment.
[3] The metal coupling agent is one or more selected from a metal alkoxide having an organic functional group, a metal chelate having an organic functional group, and a metal halogen compound having an organic functional group. Alternatively, the method for producing a surface-treated spherical boron nitride fine powder according to [2].
[4] The metal coupling agent is one or more selected from titanium coupling agents, silane coupling agents, zirconium coupling agents and aluminum coupling agents, according to the above [1] to [3]. The method for producing a surface-treated spherical boron nitride fine powder according to any one of them.
[5] A heat conductive resin composition containing the spherical boron nitride fine powder of the present invention or the spherical boron nitride fine powder obtained by the production method according to any one of the above [1] to [4].
[6] The surface of the particles is modified by wet pulverization or wet crushing by adding an oxidizing agent to the raw material, spherical boron nitride fine powder having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more. A method for producing a surface-modified spherical boron nitride fine powder, which comprises performing a quality treatment.
[7] A surface-modified spherical boron nitride fine powder obtained by the method for producing a surface-modified spherical boron nitride fine powder according to the above [6].
[8] A method for producing a surface-treated spherical boron nitride fine powder, which comprises reacting the surface-modified spherical boron nitride fine powder of the above [7] with a metal coupling agent.
[9] A surface-treated spherical boron nitride fine powder having the following (A) to (C) obtained by the production method according to any one of the above [1] to [4]; A) One or more of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga and V having a composition of 0.1 atm% or more and 3.0 atm% or less on the surface of spherical boron nitride fine particles at 10 nm. (B) The average particle size of the spherical boron nitride fine powder is 0.05 μm or more and 1 μm or less; (C) The average circularity of the spherical boron nitride fine powder is 0.8 or more. be able to. Further, (D) an organic functional group is present on the surface of the spherical boron nitride fine particles.
[10] Spherical boron nitride fine powder, which comprises adding an oxidizing agent to a raw material, spherical boron nitride fine powder, and surface-treating the particles by wet pulverization or wet crushing before the metal coupling reaction. A pretreatment method for the coupling reaction of the above, or a surface treatment method for spherical boron nitride fine powder.

Claims (7)

Spherical boron nitride fine powder having the following (A) to (C).
(A) One or two of Si, Ti, Zr, Ce, Al, Mg, Ge, Ga and V having a composition of 0.1 atm% or more and 3.0 atm% or less on the surface of spherical boron nitride fine particles at 10 nm. The above exists;
(B) The average particle size of the spherical boron nitride fine powder is 0.05 μm or more and 1 μm or less;
(C) The average circularity of the spherical boron nitride fine powder is 0.8 or more. (D) The spherical boron nitride fine powder according to claim 1, wherein an organic functional group is present on the surface of the spherical boron nitride fine particles. The organic functional group present on the surface of the spherical boron nitride fine particles includes an epoxy group which may have a substituent, a styryl group which may have a substituent, an alkyl group which may have a substituent, and a substituent. It has a vinyl group which may have a substituent, an acetylacetate group which may have a substituent, an acyl group which may have a substituent, an isocyanate group which may have a substituent, and a substituent. The spherical boron nitride fine powder according to claim 1 or 2, which is one or more selected from a tetraoctylbis group which may have a suitable cyclohexyl group and a substituent. Oxidizing agent is added to spherical boron nitride fine powder having an average particle size of 0.05 μm or more and 1 μm or less and an average circularity of 0.8 or more, which is a raw material, and the surface of the particles is modified by wet pulverization or wet crushing. The spherical boron nitride fine powder according to any one of claims 1 to 3, which is obtained by further reacting with a metal coupling agent. The spherical boron nitride fine powder according to claim 4, wherein an oxidizing agent and a water-soluble solvent are added during the surface modification treatment. The spherical boron nitride fine powder according to claim 4 or 5, wherein the metal coupling agent is one or more selected from a titanium coupling agent, a silane coupling agent, a zirconium coupling agent, and an aluminum coupling agent. The heat conductive resin composition containing the spherical boron nitride fine powder according to any one of claims 1 to 3.